1. Field of the Invention
The present invention relates to a method and a system for managing memories. More particularly, the present invention relates to a memory, an apparatus and a controller for managing multiple kinds of memories.
2. Description of Related Art
With a quick development of digital camera, cell phone and MP3, demand of storage media by customers is increased greatly. Since a flash memory has the advantages of non-volatile, energy saving, small size and none mechanical structure etc., it is suitable to function as a built-in memory for portable products, and especially for portable battery-powered products such as laptop computers or personal digital assistants. Moreover, the flash memory is also suitable to function as a storage medium for memory cards or flash drives. Since the flash drive and the memory card are widely utilized and popular in the market, the flash memory has become a hot product in the electronics industry recently.
The flash memories can be classified into single level cell (SLC) NAND flash memories and multi level cell (MLC) NAND flash memories according to different types of memory cell thereof. The flash memory is substantially divided into a plurality of physical blocks. For simplicity's sake, the physical blocks are referred to as blocks below. Generally, the block is a minimum unit that may be erased within the flash memory. Namely, each block contains a minimum number of memory cells that may be erased together. Each block is generally divided into a plurality of pages, and the page is the minimum unit that may be programmed. In other words, the page is the minimum unit that data may be written on or read from. It should be noted that according to different designs of the flash memory, the minimum programmable unit may also be a sector, namely, the page may be divided into a plurality of the sectors, and the sector is the minimum unit that may be programmed, for example, the SLC NAND flash memory using number of program (NOP) of 4.
However, since hardware structures of the flash memories fabricated by different manufacturers are different, for example, number of pages, number of blocks, number of sectors, error checking and correction (ECC) redundancy area sizes, NOPs, R/W timings and special commands of the flash memories are different, a controller of each flash memory module is limited to connect the flash memories with the same capacity and the same type, so that capacities thereof are limited. For example, if 520 MB memory spaces are required, only two 512 MB flash memories or three 256 MB flash memories can be used, and therefore cost and capacities of the flash memories are wasted.